When GTAW the root pass of a carbon steel pipe, I've always required ER70S-2 rod. This is because of it's superior deoxidizing properties compared with ER70S-3 or -6.
Recently though I've had some tube to tube sheet welding (fillet weld)with an automated GTAW machine and my standard requirement was a S-2 rod. The contractor asks wants to use S-3 or S-6 which is more readily available "It may be a pressure retaining weld, but it's only a fillet!"
Before I let him change wiresas it makes sense to me, does any one have experience allowing S-3 or S-6 wire for tube-tube sheet welds?
Thanks,
Daon
I would say first off, I think that ER-70S-2 wire is quite readily available from the local welding supply shop...I would also say that S-2 wire should be quite suitable for tube to tube sheet welds, although in my experience, I 've dealt with a lot of stainless, inconel, and monel. I have dealt with carbon and I've always welded with 70S-2 wire.
I have used ER 70S-3 for tube to tube welds on boiler waterwalls. The extra deoxidizers are not always needed from the 70S-2.
For tube to tubesheet welds I can't see a difference there but I may not be aware of the ins and outs. What is the problem you can forsee using the S-3 or 6 wire? Is there a history of a problem with this wire ?
Have a pleasant day
Gerald Austin
Hi Daon
In South Africa we use ER70S-6 almost exclusively. This includes tube to tubesheet welds. As long as you observe the general cleanliness practices normally associated with this type of joint, you should have no problem.
Regards
Niekie Jooste
Fabristruct Solutions
Niekie,
I worked at a papermill in Richards Bay SA and now that I think about it we used S-6 also.
G Austin
If you are using the GTAW process, and you need a wire that is on the high end for deoxidizers, (presumably to avoid porosity), you will probably be having fusion issues if the surface is really that dirty. I think a surface clean enough for a good GTAW weld, any of the 3 wires would be suitable.
Isn't the s-6 the one with extra deoxidizers? About twice the manganise and silicon.
Bill
S-6 does have extra Mn and Si, which are deoxidizers. The S-3 though, has Zr, Ti, and Al, which are stronger deoxidizers.
Well Now I'm confused. I though S-2 was the one with the most deoxidizers.
Does anyone have a A5.18 handy and could let me know exactly what the difference is ?
Thank you and good day
Gerald Austin
AWS A5.18/A5.18M:2001
Specification for Carbon Steel Electrodes for Gas Shielded Arc Welding
ER70S-2 = C.07 Mn.90-1.40 Si.40-.70 P.025 S.035 Ni.15 Cr.15 Mo.15 V.03 Cu.50 Ti.05-.15 Zr.02 to .12 Al.05-.15
The following differ form S-2 electrode only in the content percentage or deletion of the following elements:
ER70S-3 = C.06-.15 Si.45-.75 (no Ti Zr Al)
ER70S-4 = C.06-.15 Mn1.0-1.5 Si.65-.85 (no Ti Zr Al)
ER70S-6 = C.06-.15 Mn1.40-1.85 Si.80-1.15 (no Ti Zr Al)
ER70S-7 = C.07-.15 Mn1.50-2.0 Si .50-.80 (no Ti Zr Al)
Sorry about that, I was looking at the S-2, while typing S-3. My mistake. Thanks for catching it.
GR,
I respectfully suggest the cause of your error was not precisely as you believe.
You may not be aware of a recent variation of the old "fat-finger" virus which caused regestration of adjacent computer keyboard characters after a random number of keystrokes. I believe many of our computers suffer from this new variant as I have suspicion it also affects mine. The author of it was identified as an excentric textile engineer... the same guy who invented the fabric treatment that causes our clothes to shrink in the closet, or when otherwise stored, for no apparent reason. (all that just to say "hello")
Regards,
d
D,
I think you explanation is 100% correct.
Darn Virus.
So that's what happens, I knew my typing was suffering these days.
Huh? fat fingered virus, Darn Virus!
John Wright
I have used S-6 for many years without any problems and if your using spool wire it is sometimes more difficult to get s-2 than s-6 but if you order enough and with plenty of lead time you should not have any problems getting it. You may want to try differient suppliers if you want to stick with S-2
S2 is what is considered a triple deox wire. S6 is considered a double deox.
The main reason S2 was used in the pipe trades was as the deox capability increased, the puddle "wetness" decreased-some advantage in out of position welding.
I was taught from the old school, and Linde 65 (S2) was all that you would use on pipe. There is a new school now, I guess. I've had great luck using S6 in my tig operations. Wets much better than S2. More readily available from those "accountant run" distributors.
Hey, we are talking mild steel here on clean pipe and plate. The mechanicals between S2, S3, and S6 should be very close and may depend more on dilution than original wire chemistry.
Hope this helps
Good Luck
brande
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